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      <title>Memory Prompt - 交互式测验</title>
      <style>
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          transition: background-color 0.2s ease, border-color 0.2s ease;
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        .option-item.selected {
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        .quiz-footer {
          padding: 20px 30px;
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        .nav-btn {
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            background-color: #f8f9fa;
            border-radius: 12px;
            padding: 20px;
            width: 180px;
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            font-size: 16px;
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        }
      </style>
    </head>
    <body>
      <div class="main-wrapper">
          <div class="quiz-container">
            <div class="quiz-header">
              <h1>Memory Prompt - 交互式测验</h1>
              <p>检验你对文档内容的理解程度</p>
            </div>
            <div id="quiz-content">
                <div class="quiz-body">
                    <div class="progress-bar">
                        <div id="progress-indicator"></div>
                    </div>
                    <div id="question-container">
                      <p id="question-text"></p>
                      <ul class="options-list" id="options-list"></ul>
                    </div>
                    <div id="result-container"></div>
                    <div id="hint-container" class="hint-container"></div>
                </div>
                <div class="quiz-footer" id="quiz-footer">
                  <button id="prev-btn" class="nav-btn">上一题</button>
                  <button id="hint-btn" class="nav-btn" style="background-color: #ffc107; color: #333; box-shadow: 0 4px 12px rgba(255,193,7,0.3);">提示</button>
                  <button id="next-btn" class="nav-btn">下一题</button>
                </div>
            </div>
          </div>
      </div>

      <script>
        const quizData = [
  {
    "question": "在分布式系统中，CAP理论的'P'代表什么，为什么它通常被认为是必须保证的？",
    "options": [
      "性能 (Performance)，因为它确保了系统在高并发下的快速响应。",
      "持久性 (Durability)，因为它保证了事务提交后数据的永久保存。",
      "协议 (Protocol)，因为它定义了节点间通信的标准。",
      "分区容错性 (Partition tolerance)，因为网络问题在分布式系统中不可避免，系统必须能在节点间通信中断时继续运行。"
    ],
    "correctAnswerIndex": 3,
    "explanation": "CAP理论指出，任何一个分布式系统最多只能同时满足一致性（C）、可用性（A）和分区容错性（P）这三项中的两项。由于网络分区（如网络延迟、中断）在分布式环境中是常态，因此分区容错性（P）是必须保证的基础。设计系统时，我们通常需要在一致性（C）和可用性（A）之间做出权衡。",
    "source": "文档中「CAP 定律」部分",
    "hint": "思考一下在由多台服务器组成的系统中，哪种故障（网络、硬件、软件）是最常见且无法完全避免的？"
  },
  {
    "question": "两阶段提交协议（2PC）最主要的缺点是什么，这可能导致什么问题？",
    "options": [
      "实现过于简单，无法处理复杂事务。",
      "性能极高，但会牺牲数据一致性。",
      "同步阻塞：在第二阶段，如果协调者宕机，所有参与者资源将被锁定，导致系统不可用。",
      "只能应用于两个服务节点的事务，无法扩展。"
    ],
    "correctAnswerIndex": 2,
    "explanation": "2PC是一种强一致性的分布式事务协议。它的最大问题是同步阻塞。在提交阶段（第二阶段），如果协调者发生故障，已经锁定资源的参与者将无法收到最终指令（Commit或Abort），它们会一直处于阻塞状态，直到协调者恢复。这会长时间占用资源，并严重影响系统的可用性。",
    "source": "文档中「两阶段提交 (2PC)」部分",
    "hint": "考虑一下，如果所有参与者都在等待一个“指挥官”的最终命令，而这个“指挥官”突然失联了，会发生什么？"
  },
  {
    "question": "与ACID模型强调强一致性不同，BASE理论的核心思想是什么？",
    "options": [
      "原子性 (Atomicity), 一致性 (Consistency), 隔离性 (Isolation), 持久性 (Durability)。",
      "基本可用 (Basically Available), 软状态 (Soft state), 最终一致性 (Eventually consistent)。",
      "快速 (Fast), 可靠 (Reliable), 简单 (Simple)。",
      "同步 (Synchronous), 阻塞 (Blocking), 强一致 (Strongly Consistent)。"
    ],
    "correctAnswerIndex": 1,
    "explanation": "BASE理论是CAP理论中AP（可用性、分区容错性）方案的延伸。它描述了不同于ACID的另一种设计哲学：1. 基本可用：系统在出现故障时，允许损失部分功能，保证核心功能可用。2. 软状态：允许系统中的数据存在中间状态。3. 最终一致性：系统中的所有数据副本在经过一段时间后，最终能够达到一致的状态，而不是实时一致。",
    "source": "文档中「BASE 理论」部分",
    "hint": "BASE 理论是对 CAP 中放弃 C（强一致性）而选择 A（可用性）的策略的一种概括。"
  },
  {
    "question": "在TCC（Try-Confirm-Cancel）分布式事务模型中，'Try'阶段的主要职责是什么？",
    "options": [
      "直接提交业务操作，使数据永久生效。",
      "检查业务可行性并预留资源，为后续的Confirm或Cancel做准备。",
      "当任何一个服务的Try阶段失败时，立即回滚所有已完成的业务操作。",
      "向事务协调器注册，并声明自己将参与本次事务。"
    ],
    "correctAnswerIndex": 1,
    "explanation": "TCC模型将一个大的业务操作分解为Try、Confirm和Cancel三个阶段。'Try'阶段并非真正执行业务，而是完成所有业务可行性的检查（如检查库存、账户余额）并预留出完成事务所必需的资源（如冻结库存、冻结金额）。如果所有服务的Try阶段都成功，则进入Confirm阶段；否则，进入Cancel阶段释放预留的资源。",
    "source": "文档中「TCC (Try-Confirm-Cancel) 模式」部分",
    "hint": "在最终确认付款前，电商系统通常会先“锁定”你的优惠券和商品库存，这个“锁定”操作就类似于TCC的某个阶段。"
  },
  {
    "question": "Saga模式是如何在分布式事务失败时保证数据最终一致性的？",
    "options": [
      "通过全局事务管理器，在所有服务提交前进行统一投票。",
      "为每一个成功的正向操作（Local Transaction）提供一个对应的补偿操作（Compensating Transaction），并在失败时反向执行它们。",
      "在事务开始时锁定所有相关服务的数据，直到事务结束才释放。",
      "要求所有服务都必须在同一时刻完成提交，否则全部失败。"
    ],
    "correctAnswerIndex": 1,
    "explanation": "Saga模式是一种长事务解决方案，它将一个大事务拆分为一系列本地事务。每个本地事务都有一个对应的补偿事务。当Saga中的某个本地事务失败时，Saga协调器会调用前面已经成功执行的本地事务的补偿事务，按相反的顺序进行回滚，从而使得整个Saga事务的操作效果被撤销，达到最终一致性。",
    "source": "文档中「Saga 模式」部分",
    "hint": "想象一次旅行预订，你先订了机票，然后订酒店。如果订酒店失败了，你需要执行什么操作来取消机票预订？"
  },
  {
    "question": "在设计分布式系统接口时，为什么“幂等性”是一个至关重要的特性？",
    "options": [
      "为了保证接口的响应时间始终低于100毫秒。",
      "为了确保单个请求可以被拆分成多个更小的请求并行处理。",
      "为了防止因网络重传等原因导致同一操作被执行多次，从而产生错误的业务结果。",
      "为了让所有分布式节点的数据在任何时刻都保持绝对一致。"
    ],
    "correctAnswerIndex": 2,
    "explanation": "幂等性指的是对同一个接口的多次调用（大于等于一次），其产生的影响和结果与调用一次是相同的。在分布式系统中，由于网络延迟、超时等问题，客户端或上游服务可能会发起重试。如果接口不具备幂等性，重试操作（例如支付、下单）就可能导致数据重复，比如重复扣款。因此，保证关键操作的幂等性是构建可靠分布式系统的基础。",
    "source": "文档中「核心概念：幂等性」部分",
    "hint": "如果你按下电梯的关门按钮一次和连续按五次，结果都是关门，那么这个“按按钮”的操作就具备某种特性。"
  }
];
        console.log("Quiz Data:", JSON.parse(JSON.stringify(quizData))); // 添加这行用于调试，以可展开的JSON格式输出
        
        let currentQuestionIndex = 0;
        let score = 0;
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        const optionsListEl = document.getElementById('options-list');
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        const progressIndicatorEl = document.getElementById('progress-indicator');
        const prevBtn = document.getElementById('prev-btn');
        const nextBtn = document.getElementById('next-btn');
        const hintBtn = document.getElementById('hint-btn');
        const hintContainerEl = document.getElementById('hint-container');

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          optionsListEl.innerHTML = '';
          hintContainerEl.style.display = 'none'; // 隐藏提示
          
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            return;
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            // 如果这道题已经回答过，恢复状态
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            userAnswers[currentQuestionIndex] = optionIndex;
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            const isCorrect = optionIndex === currentQuestion.correctAnswerIndex;

            // 重新计算分数
            score = userAnswers.reduce((acc, answer, index) => {
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            }, 0);

            showResult(isCorrect, currentQuestion);
            updateNavigationButtons();
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            nextBtn.style.display = 'block';
            hintBtn.style.display = 'block'; // 显示提示按钮

            prevBtn.disabled = currentQuestionIndex === 0;
            nextBtn.disabled = false; // 最后一题时，下一题按钮不禁用，而是用于显示报告
            nextBtn.textContent = (currentQuestionIndex === quizData.length - 1) ? '查看报告' : '下一题';
            
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                hintBtn.disabled = true;
                hintContainerEl.style.display = 'none';
                hintContainerEl.textContent = ''; // 清除旧的提示内容
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                hintBtn.disabled = false;
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        function showResult(isCorrect, questionData) {
            resultContainerEl.innerHTML = ''; // 清空之前的结果
            const resultBox = document.createElement('div');
            resultBox.className = `result-box ${isCorrect ? 'correct' : 'incorrect'}`;
            
            let html = `<h3>${isCorrect ? '回答正确！' : '回答错误'}</h3>`;
            if (!isCorrect) {
                html += `<p><strong>正确答案是：</strong> ${questionData.options[questionData.correctAnswerIndex]}</p>`;
            }
            html += `<div class="explanation-text">${questionData.explanation}</div>`;
            html += `<div class="source-text">来源: ${questionData.source}</div>`;
            
            resultBox.innerHTML = html;
            resultContainerEl.appendChild(resultBox);

            // 禁用所有选项的点击事件，并高亮正确/错误答案
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                // 高亮正确答案
                if (index === questionData.correctAnswerIndex) {
                    child.classList.add('correct'); // 需要添加CSS样式
                    child.style.backgroundColor = '#d4edda';
                    child.style.borderColor = '#c3e6cb';
                }
                // 如果选错了，高亮错误选项
                if (!isCorrect && index === userAnswers[currentQuestionIndex]) {
                    child.classList.add('incorrect'); // 需要添加CSS样式
                    child.style.backgroundColor = '#f8d7da';
                    child.style.borderColor = '#f5c6cb';
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            if (currentQuestionIndex < quizData.length - 1) {
                currentQuestionIndex++;
                loadQuestion();
            } else {
                showFinalScore();
            }
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            if (currentQuestionIndex > 0) {
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                loadQuestion();
            }
        }
        
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            const currentQuestion = quizData[currentQuestionIndex];
            if (currentQuestion.hint) {
                hintContainerEl.textContent = currentQuestion.hint;
                hintContainerEl.style.display = 'block';
            } else {
                hintContainerEl.style.display = 'none';
            }
        }

        function showFinalScore() {
            document.querySelector('.quiz-body').style.display = 'none';
            document.getElementById('quiz-footer').style.display = 'none';

            const correctCount = score;
            const totalQuestions = quizData.length;
            const answeredCount = userAnswers.filter(a => a !== null).length;
            const wrongCount = answeredCount - correctCount;
            const skippedCount = totalQuestions - answeredCount;
            const accuracy = totalQuestions > 0 ? Math.round((correctCount / totalQuestions) * 100) : 0;
            const errorRate = totalQuestions > 0 ? Math.round((wrongCount / totalQuestions) * 100) : 0;

            const finalScoreHtml =
                '<div class="final-score-container">' +
                '<h2>答题报告</h2>' +
                '<div class="score-summary">' +
                '<div class="score-card">' +
                '<h3>得分</h3>' +
                '<p>' + correctCount + ' / ' + totalQuestions + '</p>' +
                '</div>' +
                '<div class="score-card">' +
                '<h3>正确率</h3>' +
                '<p>' + accuracy + '%</p>' +
                '</div>' +
                '<div class="score-card">' +
                '<h3>错误率</h3>' +
                '<p>' + errorRate + '%</p>' +
                '</div>' +
                '<div class="score-card score-details">' +
                '<table>' +
                '<tr><td>正确</td><td>' + correctCount + '</td></tr>' +
                '<tr><td>错误</td><td>' + wrongCount + '</td></tr>' +
                '<tr><td>未答</td><td>' + skippedCount + '</td></tr>' +
                '</table>' +
                '</div>' +
                '</div>' +
                '<div class="report-actions">' +
                '<button id="review-btn">回顾测验</button>' +
                '<button class="primary" onclick="location.reload()">再试一次</button>' +
                '</div>' +
                '</div>';

            let reportEl = document.querySelector('.final-score-container');
            if (reportEl) {
                reportEl.remove();
            }
            quizContentEl.insertAdjacentHTML('beforeend', finalScoreHtml);
            document.getElementById('review-btn').addEventListener('click', reviewQuiz);
        }

        function reviewQuiz() {
            const reportEl = document.querySelector('.final-score-container');
            if (reportEl) {
                reportEl.remove();
            }

            document.querySelector('.quiz-body').style.display = 'block';
            document.getElementById('quiz-footer').style.display = 'flex';
            
            currentQuestionIndex = 0;
            loadQuestion();
            updateNavigationButtons(); // Ensure nav buttons are correctly displayed
        }

        // Event Delegation for options
        optionsListEl.addEventListener('click', (event) => {
            if (event.target && event.target.matches('li.option-item')) {
                // Check if the question has already been answered
                if (userAnswers[currentQuestionIndex] === null) {
                    const selectedIndex = parseInt(event.target.dataset.index, 10);
                    selectOption(selectedIndex);
                }
            }
        });

        prevBtn.addEventListener('click', goToPreviousQuestion);
        nextBtn.addEventListener('click', goToNextQuestion);
        hintBtn.addEventListener('click', showHint);
        
        // 初始加载
        loadQuestion();
      </script>
    </body>
    </html>
  